Model aircraft ordinarily are propelled by small internal combustion engines driving propellers. Because of the scale of the device and because of its light construction it is important that vibrational stresses on the fuselage of the model airplane be minimized or prevented. Unbalances in the engine propeller combination set up vibrations which may be destructive. In addition, unbalanced conditions dissipate energy which would otherwise go toward the propulsion of the aircraft. My invention is directed to minimizing or eliminating such vibrations with little added weight in model aircraft and various other installations.